Electronic still cameras are known in the prior art for capturing images of scenes and providing the captured images to a computer for display on a computer monitor. In the above-referenced '516 and '756 applications, electronic still cameras are described for capturing images and displaying the captured images on the monitor employing a computer docking station and interface to download image data to computer memory for display and more permanent storage of the video image data. In those cameras, the camera on-board memory may then be employed to capture further images until it is again filled.
In the '756 patent, the camera is either operable by itself in a stand alone mode to store images in on-board memory or may be tethered to the computer in a docked mode to directly transfer the video image data to the computer memory. In the '516 patent, an electronic still camera is described having a resolution mode switch for selecting the pixel resolution.
Electronic still cameras of the type described in the '516 and '756 applications employ two-dimensional, charge-coupled-device (CCD) arrays of CCD photosites. The CCD photosites are overlaid with a three color filter in a checkerboard pattern. The red, green and blue analog, raw image pixel signals of the CCD photosites are clocked out in a video frame format. The raw image analog pixel signals are digitized, and luminance and chrominance pixel information is developed from the red, green and blue raw image pixel signals. Typically, the luminance signal is derived from the green filtered photosite pixel signals, and chrominance is developed from the red and blue filtered photosite pixel amplitude difference signals, with a green signal interpolation. The digitized video frame signal sets are processed within the cameras to correct for defective photosites within the array and for color balance.
The corrected digital pixel signals are compressed and formatted into a video frame signal for display on a monitor or television at the same or a later time. Typically, the video frame signals for each image captured are stored in flash EEPROM or other memory for later read-out to a personal computer (PC). A central processing unit governs the operations of the circuitry and hardware under the control of programmed operating routines.
Currently, a PC electronic still camera is being marketed by Apple Computer, Inc. which operates in high and low resolution modes to take a limited number of pictures for display through a PC interface. Such electronic still cameras are relatively complex and expensive when constructed to have high resolution and image storage capabilities.
In U.S. Pat. No. 5,220,420, an interactive multimedia system with distributed processing and storage of video frames and associated data and sound in nodes disposed throughout a cable television distribution system is described. An interface to allow users to input video images from a camcorder or VCR into a video to RF modulator in a Home Interface Control (HIC) is also described. The ability to display photographic quality images in both still frame and short full-motion segments on a home television receiver is attributed to the system, although the available video camcorders or VCRs do not support photographic quality images.
An RF to video demodulator and a video digitizer are provided in the node coupled to the HIC to demodulate and digitize the video data input from a camcorder or VCR to forward it to a regional processing center. The regional processing center converts and normalizes incoming digitized video frames into a system standardized format and stores them in an object database in each of the system nodes for selective retrieval by a viewer. No specific camcorder or video camera type is described in the '420 patent, but it is clear that a conventional analog video frame output utilizing the traditional NTSC format is supplied to the HIC to be converted to a digital format by the video digitizer 164.